nfoto Posted September 30, 2014 Share Posted September 30, 2014 Today I got a filter shipment from US seller UVIROptics containing UG-5 (thin 1.5 mm) and S-8612 (2 mm thick) filters. The combination passes a lot of UV and some of the visible bands into green, but visible is (by necessity) strongly attenuated. Unlike the Baader and its ilk this filter stack uses dyed substrates and you avoid the directional spectral change of the dichroic filter models. Although response within the visible band is very low, you can still just barely look through the stack. Here are a couple of informal photos, all taken with a Coastal Optics 60 mm f/4 APO lens on a broadband Panasonic GH-2. These are all done hand held (on my return trip from the Post Office, in fact) so image sharpness does no justice to the capability of the Coastal lens, and I did run the GH-2 up to 3200 ISO. First, getting a new w/b profile for the GH-2, using spectrally neutral targets. Unbeknownst to me, I apparently have green fingers :D (processing in PhotoNinja using a 'No profile' light source) This late in the season there are hardly any native flowers still in bloom, but I came across some sunflowers (Helianthus annuus cultivars) in the neighbourhood. The customary UV-dark centre is clearly present. The rather garish caerulean colours are obviously a persistent trait with such a filter stack, for the better or worse. None of the sunflower heads had any visible sign of marks on their ray flowers. Here is another specimen shoot through the opening of a picket fence. Too bad this arrived so late in the season, but I probably will do some more direct side-by-side comparisons with the usual Baader under studio settings later. Link to comment
Andrea B. Posted September 30, 2014 Share Posted September 30, 2014 Please show me the sunflower with each Light Source choice. I would like to see where that cyan goes with the different choices of No Profile, Daylight/Flash and the camera profile for the GH-2. If you don't like the cyan, you can always turn it off in PN. :D But it is the pink I can't stand. Blargh !!! That's just wrongo. Nice photo except for the colours this last one. Last hearthrob of summer those cardioid leaves..... Link to comment
nfoto Posted September 30, 2014 Author Share Posted September 30, 2014 Actually, the colours appeared like this directly in camera using the GH-2 preset white-balance .... The last sunflower shown had very pale almost white ray flowers, which in fact was the reason I trained the camera onto it. The caerulean markings popped up immediately in the viewfinder. Link to comment
nfoto Posted September 30, 2014 Author Share Posted September 30, 2014 I guess part of the new reality of mixing in a touch of visible colours is the inherent instability of the output colour gamut. The slightest change in illumination or direction of the camera revealed sometimes massive alterations of the colours (and image contrast) shown by the camera. Never were false colours truer :D. I guess it'll take some time and wild experimenting to make this approach settle down and mature to give useful outcomes. At present it's just a diversion from the usual run-of-mill UV stuff. Link to comment
Andrea B. Posted October 1, 2014 Share Posted October 1, 2014 mixing...the inherent instability of the output colour gamut.....sometimes massive alterations of the coloursVery interesting. Thanks for this observation. Never were false colours truer.oh la !!Well, never mind the false colour madness. The art is so fine. "-) I was thinking it would also be interesting to have a composite Vis/UV photo where the window (reflection) was Visible and the house/sunflower was UV. Link to comment
nfoto Posted October 1, 2014 Author Share Posted October 1, 2014 A composite UV/Visible done with a hand-held camera surely would go towards the Fine Art of False Colours :D Maybe on another occasion. I'll keep it in mind. Link to comment
Andrea B. Posted October 1, 2014 Share Posted October 1, 2014 Supposing a viewer simply stumbled across a false colour UV photograph in a gallery or a museum with absolutely no knowledge of the medium or how it works.......If that false colour UV photograph does not stand alone, all by itself, as a Photograph, then...... How many times have we chanted this refrain? We should set it to music. :D (Recently I've concentrated too hard on documentary work and seem to have lost the idea of a Photograph.) Link to comment
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